Lens barrel and camera with lens barrel

ABSTRACT

A lens barrier is opened/closed by a barrier drive cylinder disposed on an outer peripheral side of a lens. The barrier drive cylinder is rotated by a rotation of a cam cylinder together with a first cylinder so as to move forward and backward. In the course of a movement of the lens from a retracted position to a shooting position, the barrier drive cylinder rotates such that a drive ring biased to an opening direction by a spring is driven into an opening direction. The barrier is, thus, opened. When the lens is moved from the shooting position to the retracted position, the operation reverse to the aforementioned is performed to close the barrier. An annular seal member is provided into the space between the barrier drive cylinder and the first cylinder so as to prevent water from entering into the barrel.

The disclosure of the following priority applications are incorporatedherein by reference:

-   -   Japanese Patent Application No.2003-427161 filed Dec. 24, 2003;        and    -   Japanese Patent Application No.2004-72524 filed Mar. 15, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel having a lens barrier anda camera having the lens barrel, which are particularly considered tohave a dust-proof/drip-proof structure.

2. Description of the Related Art

A lens-barrel that has a lens barrier which can be opened/closed atpositions for exposing a photographic lens and covering its frontsurface respectively, has been known as disclosed in, for example,Japanese Laid-Open Patent Publications No. 2001-21559 and No. H5-19331.The lens barrier of the aforementioned lens barrel is operated by arotating member that rotates about an optical axis.

The lens barrel is required to have a dust-proof/drip-proof structure soas to be protected from undesirable dust or droplet such that functionsof various elements and an optical performance are not deteriorated.Water droplets that enter through an opening for the lens exposure inthe opened state of the lens barrier tend to be accumulated in a barrierretraction space rather than being drained.

The lens barrel disclosed in each of the aforementioned publications isnot provided with the dust-proof/drip-proof structure for the lensbarrier and a portion around the mechanism for driving the lens barrier.The aforementioned disclosed lens barrel is not provided with thestructure for discharging water that has entered into the lens barrel.

SUMMARY OF THE INVENTION

A lens barrel according to the first aspect of the invention is providedwith a lens provided in a lens chamber within the lens barrel, a lensbarrier that is opened and closed in front of the lens, a barrier drivecylinder provided on an outer peripheral side of the lens so as to beallowed to rotate about an optical axis relative to a member provided onan inner peripheral side of the barrier drive cylinder, a first linkmechanism that rotates the barrier drive cylinder, a second linkmechanism that opens and closes the lens barrier interlocking with arotation of the barrier drive cylinder, and an annular seal member thatis provided into a space between the barrier drive cylinder and themember provided on the inner peripheral side over an entirecircumference.

In the case where the lens is allowed to move forward and backward alongthe optical axis for performing an operation of zooming or focusing, itis preferably structured such that the first link mechanism interruptsthe rotation of the barrier drive cylinder when the lens moves forwardand backward for performing the operation of zooming or focusing.

When the lens is allowed to move forward and backward in a range betweena shooting position and a non-shooting position along the optical axis,the first link mechanism preferably rotates the barrier drive cylinderinterlocking with the lens that moves forward and backward.

The first link mechanism may be structured to rotate the barrier drivecylinder only when the lens moves in a part of the range between theshooting position and the non-shooting position.

The first link mechanism may comprise a rotary cylinder that rotatesabout the optical axis on the outer peripheral side of the lens so as togenerate a force that moves the lens and the barrier drive cylinderalong the optical axis, and a straight guide member that guides the lensto move straight along the optical axis and applies a rotating forcearound the optical axis to the barrier drive cylinder that moves alongthe optical axis.

The second link mechanism may comprise a drive force generation memberthat generates a drive force for opening and closing the lens barrier,and a transfer mechanism that opens the lens barrier through a transferof the drive force to the lens barrier interlocking with a rotation ofthe barrier drive cylinder in one direction and closes the lens barrierwithout the transfer of the drive force interlocking with a rotation ofthe barrier drive cylinder in an opposite direction. The transfermechanism is provided closer to a front of the lens barrel than the sealmember.

A lens barrel according to a second aspect of the invention is providedwith lenses provided in a lens chamber within the lens barrel, a lensbarrier that is opened and closed in front of the lenses, a barrierblock that is provided near an inlet of the lens chamber. The barrierblock is capable of holding the lens barrier in an open state and aclosed state, and has a barrier retraction space in which the lensbarrier in an opened state is received. As the barrier block moves alongthe optical axis, a volume of a rear portion of the lens chamberchanges. The above-structured barrier block is provided with a drainhole which communicates the barrier retraction space with an outside ofthe lens barrel, and an air passage formed near the drain hole whichcommunicates the barrier retraction space with the rear portion of thelens chamber. Accordingly an air flow directed from the rear portion ofthe lens chamber toward the barrier retraction space is generated in theair passage when the barrier block moves backward.

The barrier unit includes at least a part of the lenses and a holdingmember thereof, and a part of the air passage may be an air hole formedin the holding member.

It is preferable to dispose a metal function member within the lensbarrel in the air passage so as to prevent rusting. It is preferable toseal the air passage with a gas permeable water-repellent sheet so as toprevent water from entering into the inside of the lens barrel. Aplurality of the air passages formed in the barrier block makes sure todischarge air within the lens chamber to the outside.

The first and the second aspect of the invention may be combined to formthe lens barrel according to the third aspect of the invention. The lensbarrel according to the third aspect may employ a metal spring as thesecond link mechanism in the form of the barrier drive force generationmember. The barrier drive force generation member may be disposed in theair passage so as to prevent rusting. The camera that contains the lensbarrier according to the first to the third aspects of the inventioneffectively prevents water from entering thereinto, and effectivelydrains the water that has been entered and accumulated therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a camera according to the first embodiment;

FIG. 2 is a front view of the camera as shown in FIG. 1;

FIG. 3 is a cross sectional view of a lens barrel taken along lineIII-III shown in FIG. 2 when the lens barrier is closed;

FIG. 4 is a cross sectional view of the lens barrel taken along lineIV-IV shown in FIG. 2 when the lens barrier is closed;

FIG. 5 is a development of a guide key;

FIG. 6 is an expanded view of a portion VI shown in FIG. 5 as a barrierdrive cam formed in the guide key;

FIG. 7 is a view similar to FIG. 3 when the lens barrier is opened;

FIG. 8 shows the lens barrier viewed from a back side of the camera;

FIG. 9 shows the lens barrier in a closed state viewed from a front sideof the camera;

FIG. 10 is a view similar to FIG. 9 when the lens barrier is opened;

FIG. 11 is a view of a barrier drive mechanism viewed from the back sideof the camera when the lens barrier is closed;

FIG. 12 is a view similar to FIG. 11 when the lens barrier is opened;

FIG. 13 is a front view of a camera according to the second embodiment;

FIG. 14 is a cross sectional view of a lens barrel taken along lineXIV-XIV shown in FIG. 13 when a lens barrier is closed;

FIG. 15 is a cross sectional view of the lens barrel taken along lineXV-XV shown in FIG. 13 when the lens barrier is closed;

FIG. 16 is a view similar to FIG. 14 when the lens barrier is opened;

FIG. 17 shows the lens barrier viewed from the back side of the camera;

FIG. 18 is an expanded view that represents a portion located near adrain hole and an air hole as shown in FIG. 14;

FIG. 19 shows a barrier drive ring holding member viewed from a front ofan optical axis; and

FIG. 20 is a view corresponding to FIG. 18, which represents a modifiedexample of the second embodiment.

DESCRIPTION OF THE PREFFERED EMBODIMENT First Embodiment

A first embodiment according to the invention will be describedreferring to FIGS. 1 to 12.

FIGS. 1 and 2 respectively show a top view and a front view of a camera(digital still camera) according to the first embodiment. A power button1, a shutter button 2, and zoom buttons 3, 4 are provided on a topsurface of the camera. A zoom motor 11 is driven upon depression of thezoom button, and the resultant rotation is transferred to a cam cylinder21 of a lens barrel LB via a worm 12 and a gear set 13. The rotation ofthe cam cylinder 21 allows a zooming operation. When the power is turnedoff, the lens barrel LB is brought into a retracted position(non-shooting position, non-photographing position). The zoom motor 11serves as a drive source that brings the lens barrel into the retractedposition and projects it into the shooting position (photographingposition), respectively. Under the zoom control, an end of a reflectiontape applied onto the cam cylinder 21 is detected by a photo reflectorPR and a position when detecting the end of the reflection tape is setas a reference position. A rotation amount of the cam cylinder 21 fromthe reference position is controlled through detection of the rotationof the worm 12 by a photo interrupter PI.

The lens barrel LB incorporates a lens barrier 40 (hereinafter simplyreferred to as a barrier) that opens/closes in front of the lens. Thedetailed description with respect to the structure and the drivemechanism for the barrier 40 will be explained later. The barrier isclosed by four barrier blades that cover an opening 51 c for exposure ofthe lens such that the photographic lens is protected.

The description with respect to the lens drive mechanism, the barrier,the barrier operation mechanism, and the drip-proof structure of thelens barrel LB will be explained referring to FIGS. 3 to 12 in order.

<Lens Drive Mechanism>

FIGS. 3 and 4 are cross sectional views of the lens barrel LB takenalong lines III-III and IV-IV shown in FIG. 2 respectively when the lensis in a retracted position. A fixed cylinder 22 that is fixed to acamera body has the cam cylinder 21 on its inner periphery. The camcylinder 21 is rotated about an optical axis by the driving force of thezoom motor 11 that has been transferred to a gear portion 21 a of thecam cylinder 21. A cam follower 21 b provided on the cam cylinder 21 isengaged with a cam of the fixed cylinder 22. Accordingly the camcylinder 21 moves backward and forward along the optical axis whilerotating relative to the fixed cylinder 22, that is, the camera body.

A guide key 23 provided on the inside of the cam cylinder 21 isrotatably held at a holding portion 23 a (FIG. 4) relative to the camcylinder 21 so as to move backward and forward along the optical axistogether with the cam cylinder 21. A stopper 22 a of the fixed cylinder22 prevents the rotating operation of the guide key 23. Accordingly theguide key 23 does not rotate relative to the fixed cylinder 22. As thedevelopment of FIG. 5 shows, the guide key 23 has two kinds of keygrooves (straight guide grooves) along the optical axis, that is, threegrooves 23 b and three grooves 23 c, respectively. Those grooves serveto guide first-group lenses L1 and second-group lenses L2 along theoptical axis, respectively as later described.

The first-group lenses L1 are held by a first-group frame 24 that ispushed into a first-group cylinder 25 so as to be held. A cam follower25 a formed on the first-group cylinder 25 goes through the key groove23 b of the guide key 23 (FIG. 5) so as to be engaged with a cam groovefor driving the first-group lenses of the cam cylinder 21. Accompaniedwith the rotation of the cam cylinder 21, the first-group cylinder 25,that is, the first-group lenses L1 are allowed to move backward andforward along the optical axis relative to the cam cylinder 21.Meanwhile the second-group lenses L2 are held by a second-group frame 26together with the shutter 27. A cam follower 26 a of the second-groupframe 26 goes through the key groove 23 c (FIG. 5) of the guide key 23so as to be engaged with a cam groove for driving the second-grouplenses of the cam cylinder 21. Accompanied with the rotation of the camcylinder 21, the second-group lenses L2 and the shutter 27 are allowedto move backward and forward along the optical axis relative to the camcylinder 21.

A third-group lens L3 held by a third-group frame 28 is formed as afocus lens, which is driven along the optical axis by a not-shown focusmotor (stepping motor). Apertures 31, 32, an optical low pass filter 33,an image-capturing element 34 such as a CCD, a rear cover 35 of thecamera, and a front cover 36 of the camera are provided.

<Barrier Structure>

An outer barrier cover 51 attached to a leading end of the first-groupcylinder 25 has an opening 51 c formed therein for exposure of the lens.In case of closing the barrier, four barrier blades 41A, 41B, 42A and42B serve to cover the opening 51 c as shown in FIG. 3. In case ofopening the barrier, those blades that have been released are retractedinto a barrier retraction space SP1 defined by the inner and outerbarrier covers 52, 51 so as to be stored overlapped therein as shown inFIG. 7.

FIG. 8 shows the barrier 40 viewed from the image-capturing element, andFIGS. 9 and 10 respectively show the barrier 40 viewed from the frontend of the camera in the direction IX as shown in FIG. 4. The upperbarrier blades 41A, 42A are supported rotatably about an axis 51 a thatprotrudes from the barrier cover 51. The lower barrier blades 41B, 42Bare supported rotatably about an axis 51 b in the same manner asaforementioned. The axes 51 a and 51 b are provided with blade drivesprings (torsion springs) 45A, 45B, respectively. Ends of the springs45A and 45B are respectively held at spring holding portions 41Aa and41Ba of the respective barrier blades 41A, 41B, and the other ends areheld at spring holding portions 52 a, 52 b of the barrier cover 52respectively. The bias force of those springs 45A, 45B serve to biasthose four barrier blades toward a barrier closing direction. When thebarrier is closed, leading ends of the barrier blades 41A and 41B abutwith each other. The barrier blades 42A and 42B are laid on and underthe barrier blades 41A and 41B, respectively.

Back surfaces of the barrier blades 41A and 41B have blade drive shafts41Ab and 41Bb as shown in FIG. 8 so as to protrude therefrom,respectively. Front surfaces of the barrier blades 41A and 41B haveblade link shafts 41Ac and 41Bc as shown in FIG. 9 so as to protrudetherefrom, respectively. In the state where the barrier is closed, whena barrier drive ring 53 (described later) rotates in a barrier openingdirection so as to apply the force in the barrier opening direction tothe blade drive shafts 41Ab, 41Bb, the barrier blades 41A and 41B startrotating about the shafts 51 a and 51 b respectively against the biasforce of the springs 45A and 45B. As the barrier blades 41A and 41B moveto reach a predetermined barrier opening position, the blade link shafts41Ac and 41Bc abut on the barrier blades 42A and 42B, respectively. As aresult, the barrier blades 42A and 42B start opening.

FIG. 10 shows the barrier in the state where the respective barrierblades are in fully opened positions. In the fully opened state, whenthe barrier drive ring 53 (described later) rotates in the barrierclosing direction to interrupt the application of the drive force foropening the barrier to the blade drive shafts 41Ab and 41Bb, each biasforce of the blade drive springs 45A, 45B serves to close the blade(FIGS. 8, 9). The description with respect to the barrieropening/closing operation will be described later.

<Barrier Drive Mechanism>

The aforementioned barrier blades are opened through transfer of thebias force of a bias spring 55 to the blade drive shafts 41Ab and 41Bbvia the barrier drive ring 53 as shown in FIG. 11. The barrier drivering 53 is joined through bayonet coupling with an engaging pawl 54 b ofa barrier drive ring holding member 54 as shown in FIG. 3 screwed to thefirst-group cylinder 25 so as to be rotatable about the optical axisrelative to the barrier drive ring holding member 54. The bias spring 55is interposed between a spring holding portion 53 a of the barrier drivering 53 and a spring holding portion 54 a of the holding member 54 so asto bias the barrier drive ring 53 counterclockwise as shown in FIG. 11.The bias spring force for opening the barrier applied to the barrierdrive ring 53 is blocked by a barrier drive cylinder 56 (describedlater) until it is required to open the barrier. When it is required toopen the barrier, the barrier drive cylinder 56 is operated into abarrier opening direction such that the bias force of the bias spring 55serves to rotate the barrier drive ring 53 in the opening direction soas to open the barrier blades.

The barrier drive ring 53 and the bias spring 55 are disposed in thespace SP2 (FIG. 7) defined by the inner barrier cover 52 and the barrierdrive ring holding member 54. The space SP2 will be referred to as thedrive ring space.

The spring holding portion 54 a and the engaging pawl 54 b maybe formedintegrally with the first-group cylinder 25. However, if theabove-described pawl-like member is integrally formed with thefirst-group cylinder 25, a hole has to be formed around the pawl-likemember for the purpose of eliminating the undercut portion. Accordinglywater is likely to enter into the lens barrel through the aforementionedhole. In the embodiment, the holding member 54 is provided with thepawl-like member so as to prevent water from entering into the frontsurface of the first-group cylinder 25. Then the holding member 54 isattached by screws to the first-group cylinder 25 so as to avoidformation of the hole, resulting in the improved drip-proof structure.

FIG. 11 shows the barrier drive ring 53 in the state where itscounterclockwise rotation is interrupted by a pawl 56A of a barrierdrive cylinder 56 (described later) while keeping the barrier bladesclosed. Accompanied with the counterclockwise rotation of the barrierdrive cylinder 56 in response to the request for opening the barrier,the pawl 56A is moved counterclockwise. Accordingly the counterclockwiserotation of the barrier drive ring 53 is allowed by the bias force ofthe bias spring 55. The barrier drive ring 53 is provided with a pair ofabutment portions 53 b symmetrical with respect to the axis of thebarrier drive ring 53. The counterclockwise rotation of the barrierdrive ring 53 brings the pair of abutment portions 53 b into abutment onthe blade drive shafts 41Ab and 41Bb. The barrier blades are released bymoving the blade drive shafts 41Ab and 41Bb to the position as shown inFIG. 12.

A bayonet portion 56 b (FIG. 3) of the barrier drive cylinder 56 havingthe pawl 56A for limiting the rotation is joined through bayonetcoupling with the first-group cylinder 25. Accordingly the barrier drivecylinder 56 moves along the optical axis together with the first-groupcylinder 25. The barrier drive cylinder 56 is allowed to rotate relativeto the first-group cylinder 25 only in a certain angular range. A camfollower 56 c (FIG. 4) of the barrier drive cylinder 56 is engaged withthe barrier drive cam 23 d (FIGS. 5, 6) formed in the guide key 23. Thecam cylinder 21 moves along the optical axis while rotating with the camgroove of the fixed cylinder 22. The guide key 23 moves along theoptical axis together with the cam cylinder 21, but does not rotaterelative to the fixed cylinder 22. The first-group cylinder 25 is movedaccompanied with the rotation of the cam cylinder 21 along the opticalaxis together with the barrier drive cylinder 56. A distance of themovement of the first-group cylinder 25 along the optical axis isdifferent from that of the cam cylinder 21. The barrier drive cylinder56 moves along the optical axis relative to the guide key 23, whichallows the barrier drive cylinder 56 to rotate upon receipt of therotating force from the barrier drive cam 23 d. The pawl 56A is drivento be moved between the position (FIG. 11) at which the rotation of thebarrier drive ring 53 is interrupted and the position (FIG. 12) at whichthe rotation is allowed. The detailed operations will be explainedlater.

<Drip-Proof Structure>

A ring-shaped drip-proof rubber member 71 is fit to the space defined bythe front cover 36 of the camera and the cam cylinder 21 over an entirecircumference. A ring-shaped drip-proof rubber member 72 is also fit tothe space defined by the cam cylinder 21 and the barrier drive cylinder56 over an entire circumference. A ring-shaped drip-proof rubber member73 is further fit to the space defined by the barrier drive cylinder 56and the first-group cylinder 25 over an entire circumference. An outerperipheral surface of the drip-proof rubber member 71 is bonded to thefront cover 36 of the camera, and an inner peripheral surface is incontact with the outer peripheral surface of the cam cylinder 21. Anouter peripheral surface of the drip-proof rubber member 72 is bonded tothe cam cylinder 21, and an inner peripheral surface is in contact withan outer peripheral surface of the barrier drive cylinder 56. An outerperipheral surface of the drip-proof rubber member 73 is bonded to thebarrier drive cylinder 56, and an inner peripheral surface is in contactwith the outer peripheral surface of the first-group cylinder 25. Thatis, each of the above-described drip-proof rubber members 71 to 73 isbonded to the inner peripheral surface of each of the outer members, andin tight contact with the inner member through elastic force so as toprevent water droplets and dust from entering through the respectivegaps. These drip-proof rubber members 71 to 73 serve to perform ashading function. The gap between the first-group frame 24 and thefirst-group cylinder 25 is sealed with the silicon.

Each of FIGS. 3, 4 and 11 represents the state where the lens barrel LBis in the retracted position, and the respective blades of the barrier40 are closed. In the aforementioned state, the cam follower 56 c of thebarrier drive cylinder 56 is in the position designated as Pr shown inFIG. 6 relative to the barrier drive cam 23 d of the guide key 23. Whenthe power of the camera is turned on, the zoom motor 11 rotates, and theaforementioned function causes the cam cylinder 21 to be projected whilebeing rotated, and the first-group cylinder 25 and the second-groupframe 26 moves backward and forward relative to the cam cylinder 21.

The guide key 23 that moves backward and forward together with the camcylinder 21 moves relative to the barrier drive cylinder 56, which isprojected together with the first-group cylinder 25, in the arrowdirection as shown in FIG. 6. Accordingly the cam follower 56 c receivesthe rotating force from the cam 23 d until it reaches the position Pm,and the barrier drive cylinder 56 rotates. This allows the pawl 56A ofthe barrier drive cylinder 56 to rotate counterclockwise as shown inFIG. 11, and the barrier drive ring 53 is rotated in the same directionby the bias force of the bias spring 55. As the barrier drive ring 53rotates to a certain degree, the pair of the abutment portions 53 b abuton the blade drive shafts 41Ab and 41Bb respectively so as to be driven.Then four barrier blades 41A, 41B, 42A and 42B are released to bestopped in abutment on the stopper at the released side, thus stoppingthe barrier drive ring 53. The barrier drive cylinder 56 keeps rotatingeven after the drive ring is stopped. It stops when the cam follower 56c reaches the position Pm.

The barrier blades are constantly biased toward the closing direction bythe blade drive springs 45A and 45B. As the bias force of the biasspring 55 is greater than that of the blade drive springs 45A and 45B,those blades 41A, 41B, 42A and 42B are held opened.

The cam cylinder 21, guide key 23, the first-group cylinder 25 and thebarrier drive cylinder 56 further move forward until the lenses L1 andL2 reach the “wide” end position. Then photographing is allowed. The camfollower 56 c at this time is located on the position Pw. The camfollower 56 c moves in parallel with the optical axis of the barrierdrive cam 23 d in the range between the position Pm and the position Pw.Until then, it is not influenced by the rotating force, and the barrierdrive cylinder 56 does not rotate. Upon operation of the zoom buttons 3and 4 for zooming, the first-group cylinder 25 and the second-groupframe 26 move backward and forward along the optical axis. Thefirst-group cylinder 25 once retracts toward the CCD in accordance withthe zooming to a “tele” side, and then moves forward from the halfwayposition. The barrier drive cylinder 56 that moves together with thefirst-group cylinder 25 has the same movement as described above. Thecam follower 56 c moves to pass the positions Pw, Pm, Pw, and Pt (“tele”end) in this order, and moves in the reverse order in case of zooming tothe “wide”. Accordingly, the cam follower 56 c is not influenced by thedrive force from the barrier drive cam groove 23 d, thus preventing therotation of the barrier drive cylinder 56.

FIG. 7 shows the operational state in which the cam follower 56 c islocated on the position Pm (the intermediate position between the “tele”end and the “wide” end) by zooming. In this state, the degree ofprojection of the first-group cylinder 25 and the barrier drive cylinder56 from the cam cylinder 21 become the smallest among those during thezooming. There may be the case where the lens barrel is brought intosuch state when the cam follower 56 c reaches the “wide” end position.

When the power of the camera is turned off, the lens barrel LB is drivento the retracted position. As it approaches the retracted position, therelative movement of the barrier drive cylinder 56 that moves togetherwith the first-group cylinder 25, and the guide key 23 that movestogether with the cam cylinder 21 causes the cam follower 56 c of thebarrier drive cylinder 56 to move from the position Pm to the positionPr. Accordingly the cam follower 56 c receives the rotating force fromthe cam 23 d, and the barrier drive cylinder 56 rotates in the directionreverse to the one as aforementioned (the clockwise direction as shownin FIG. 12). The pawl 56A of the barrier drive cylinder 56 rotates thebarrier drive ring 53 clockwise against the bias spring 55 so as torelease the force applied to the blade drive shafts 41Ab, 41Bb foropening. Then the respective barrier blades are closed by the bias forceof the blade drive springs 45A and 45B.

The drip-proof rubber member 73 that is fit between the barrier drivecylinder 56 and the first-group cylinder 25 slidably moves on the outerperipheral surface of the first-group cylinder 25 upon rotation of thebarrier drive cylinder 56 such that the sliding friction force isgenerated. Such friction force becomes the rotational load of thebarrier drive cylinder 56. The embodiment of the invention is structuredso that the bias force (barrier drive force) of the bias spring 55 istransferred to the barrier 40 interlocking with the rotation of thebarrier drive cylinder 56 to open the barrier 40 rather than the casewhere the barrier drive cylinder 56 directly drives the barrier 40.Accordingly the friction force does not function as the resistanceagainst the bias spring 55 without giving an adverse effect to theopening operation of the barrier. The consideration with respect to theuse of a large bias spring sufficient to resist the friction force doesnot have to be made, resulting in reduced cost and space.

The barrier drive cylinder 56 is rotated interlocking with the drivingof the lens. The effect of the barrier drive cam 23 d keeps the barrierdrive cylinder 56 from rotating during the time other than that foroperating the barrier. Especially at the zooming operation, it is neverrotated. This makes it possible to minimize the sliding movement of thedrip-proof rubber member 73, thus improving the dust-proof anddrip-proof functions. As the friction force resulting from the slidingmovement of the drip-proof rubber member 73 is never generated at thezooming operation, such friction force does not serve as the load of themotor. As the rotating angle of the barrier drive cylinder 56 issubstantially small as shown in FIGS. 11 and 12, the consideration foravoiding the interference of the barrier drive cylinder to theperipheral members may be minimized, thus saving the space. In thestructure where the barrier drive cylinder is constantly rotated whenthe lens is driven (including zooming) as disclosed in JapaneseLaid-Open Patent Publication No. 2001-215559, the friction force of thedrip-proof rubber member serves as the motor load during the zoomingoperation. As the rotating amount of the pawl is also increased, theconsideration for avoiding the interference to the peripheral membershas to be made.

The barrier drive cylinder 56 rotates upon receipt of the rotating forcefrom the barrier drive cam 23 d formed in the guide key 23. It may bestructured to receive the rotating force from the cam formed in the camcylinder 21 rather than that formed in the guide key 23. As the camcylinder 21 has been already provided with the cam for driving twogroups of lenses L1 and L2, if the cam for driving the barrier isfurther added, the length or the thickness of the cam cylinder 21 has tobe increased depending on circumstances. Meanwhile, the guide key 23 isprovided with two guide grooves 23 b and 23 c. As the rotating angle ofthe barrier drive cylinder 56 is substantially small as described above,most part of the cam 23 d is straight as shown in FIGS. 5 and 6. Thenthe thickness or the length of the guide key 23 does not have to beincreased for adding the cam 23 d to the guide key 23.

As has been described above, the first-group cylinder 25 is arrangedjust inside of the barrier drive cylinder 56. It is inevitable to fitthe drip-proof rubber member 73 to the space between the barrier drivecylinder 56 and the first-group cylinder 25. In the structure having theother member, which can rotate relatively to the barrier drive cylinder56, between the barrier drive cylinder 56 and the first-group cylinder25, the drip-proof rubber member 73 is fit to the space between thebarrier drive cylinder 56 and the other member.

Second Embodiment

A camera that has a lens barrel according to the second embodiment willbe described referring to FIGS. 13 to 19. In this embodiment, anexplanation will be only made with respect to the elements differentfrom those of the first embodiment, and the explanation of the sameelements as those of the lens barrel in the first embodiment anddesignated with the same reference numerals, thus, will be omitted. Thelens barrel according to the second embodiment is provided with a drainstructure that drains water which has accidentally entered into the lensbarrel.

The drain structure as the feature of the second embodiment will bedescribed referring to FIGS. 13 to 17.

The camera has drain holes 51 h formed in a barrier cover 51 fordraining. The outer barrier cover 51 in front of the lens barrel LB hasa plurality of small holes 51 h (hereinafter referred to as drain holes)at the portion under an opening 51 c for exposure of the lens. Theopening 51 c is opened/closed with the lens barrier 40 (hereinaftersimply referred to as a barrier) as described above. The opening 51 c isclosed by four barrier blades so as to protect the photographic lenses.

The aforementioned drain holes 51 h are formed in substantially thelowest portion of the outer barrier cover 51. As shown in the expandedview in FIG. 18, a barrier retraction space SP1 is communicated with anoutside of the camera through the drain holes 51 h. That is, the drainholes 51 h are formed for the purpose of draining water droplets thatreside in the lower portion of the barrier retraction space SP1 to theoutside. Meanwhile, an air hole 52 h is formed in the lowest portion ofan inner barrier cover 52 at a position mostly opposite to the drainholes 51 h. The barrier retraction space SP1 is communicated with thedrive ring space SP2 through the air hole 52 h.

The barrier drive ring holding member 54 and the first-group cylinder 25have air holes 54 h and 25 h at the lowest portions thereof,respectively. Those air holes 54 h and 25 h are partially overlappedwith respect to the optical axis as shown in FIG. 19 representing theview of the barrier drive ring holding member 54 from the front of theoptical axis. Accordingly the drive ring space SP2 is communicated witha rear space in the barrel (rear space of lens chamber) SP3 via the airholes 54 h and 25 h. The air hole 25 h formed in the first-groupcylinder 25 is tapered where its opening area is reduced as itapproaches the front of the camera.

Referring to FIG. 19, a screw hole 54 d is formed with which the outerbarrier cover 51 is fixed, and a screw BS is used for fixing the barrierdrive ring holding member 54 to the first-group cylinder 25.

The air holes 52 h, 54 h, 25 h and the space SP2 formed in therespective members constitute an air passage through which thecommunication between the barrier retraction space SP1 and the rearspace SP3 in the barrel is made. The air passage is formed at a positionmostly opposite to the drain holes 51 h. The barrier covers 51, 52, thebarrier drive ring holding member 54 and the first-group cylinder 25 arecombined to constitute a single lens block or a barrier block BR thatdoes not rotate about the optical axis. Accordingly each position of theair passage and the drain holes 51 h formed in the block BR is keptunchanged irrespective of the operation state of the lens barrel.

In other words, the barrier block BR is provided near an inlet of thelens chamber so as to be movable along the optical axis and to hold thestate of the lens barrier that can be opened and closed. The barrierblock BR has the barrier retraction space SP1 formed therein foraccommodating the lens barrier in the opened state. As the barrier blockBR moves along the optical axis, the volume of the rear space within thelens chamber is changed.

As described above, the rear space SP3 in the lens barrel represents thespace within the lens barrel, which is closer to the rear of the camerathan the first-group lenses L1, that is, the lens block BR.

A tapered air hole 25 h 2 is formed in the upper portion of thefirst-group cylinder 25 as shown in FIG. 19, through which thecommunication between the rear space SP3 in the lens barrel and thedrive ring space SP2 is made. The drive ring space SP2 is communicatedwith the barrier retraction space SP1 via a center opening of the innerbarrier cover 52. That is, another air passage is formed in the upperportion of the lens barrel to communicate the barrier retraction spaceSP1 with the rear space SP3 in the lens barrel. A water repellent sheet101 is fixed to the front surface of the first-group cylinder 25 so asto cover each end of the respective taper holes 25 h and 25 h 2. Thewater repellent sheet 101 is generally formed of such material as awater repellent polyester (finished with silicone and fluoride) fiber asan air permeable material that repels water for the use in the closingmaterial field.

The draining operation will be described hereinafter.

The aforementioned drip-proof rubber members 71 to 73 prevent water fromentering into the lens barrel as least as possible. However, it may bethe case that water enters into the barrier retraction space SP1 throughthe opening 51 c upon opening of the barrier or during itsopening/closing operation. Even if the barrier is closed, water mayenter into the barrier retraction space SP1 through the gap between thebarrier blade and the outer barrier cover 51 in the same way asdescribed above. The residual water in the barrier retraction space SP1is drained through the drain hole 51 h formed in the outer barrier cover51. The surface tension of the water makes it difficult to let suchwater to be drained by itself unless the size of the drain hole 51 h isincreased to a certain degree. However, if the size of the drain hole 51h is increased, the characteristic with respect to the design islimited. Moreover it is difficult for the small sized lens barrel tofurther increase the size of the drain hole. Therefore, the hole 51 hhas to be limited to be extremely small. The residual water may be heldin the camera unless it is forcedly drained by shaking of the camera bythe user.

In the second embodiment, the air passage formed in the lens block BR(airholes 52 h, 54 h, 25 h and space SP2) further facilitates thedraining. When the lens barrel is retracted, the lens block BR movesbackward to reduce the volume of the rear space SP3 in the lens barrel.At this moment, an air flow directed from the rear space SP3 to thebarrier retraction space SP1 is generated as shown by an arrow in FIG.18. As the air passage is formed at the lower portion of the lens blockBR, the aforementioned air flow serves to force the residual water inthe lower portion of the barrier retraction space SP1 to the outsidethrough the drain holes 51 h. Even if the size of the drain holes 51 his small, the residual water can be effectively drained outside withoutshaking of the camera by the user.

As the air hole 25 h that partially constitutes the air passage has atapered shape, the pressure of air that is fed forward through the airhole 25 h becomes high, thus enhancing the draining performance.Additionally the formation of the tapered hole can be easilyfacilitated. As the water repellent sheet 101 is attached to the frontend of the tapered hole 25 h, the entrance of water backward of suchwater repellent sheet can be prevented as much as possible.

In the case where the camera is used in a heavy rain, which allowsentrance of much water into the barrier retraction space SP1 to preventthe flow of air by blocking the air passage, it may be difficult todrain such water. In the second embodiment, the air flow directed fromthe rear space SP3 in the lens barrel to the drive ring space SP2 isgenerated in the tapered hole 25 h 2 formed in the upper portion of thefirst-group cylinder 25. Such air flow serves to force the water in thebarrier retraction space SP1 to the outside. Accordingly draining of thewater in the barrier retraction space SP1 and the lower air passage maybe facilitated. As the water repellent sheet 101 is attached to the endof the hole 25 h 2, entrance of water backward may be prevented as muchas possible as aforementioned.

In the second embodiment, the bias spring 55 is provided in the middleof the air passage so as to rotate the barrier drive ring 53 as shown inFIG. 18. The bias spring 55 formed of a metal is likely to be rusted bywater. However, air flowing through the air passage is expected to drythe spring 55 so as to be protected from being rusted.

FIG. 20 shows a modified example of the second embodiment. The sameelements that exhibit the same functions as those in the firstembodiment will be designated with the same reference numerals. In thisexample, the drain holes 56 h are formed in the lower-end portion of theperipheral surface of the barrier drive cylinder 56 instead of thebarrier cover, that is, the portion corresponding to the bottom of thebarrier retraction space SP1 for drainage. In this case, as the airpassage formed of the air holes 52 h, 54 h, 25 h and the space SP2 isformed in the vicinity of the drain holes 56 h, the air flow mayfacilitate the drain operation effectively as aforementioned.

The barrier drive cylinder 56 as a constituent of the lens block BRrotates about the optical axis relative to the other elements such asthe barrier covers 51, 52, the barrier drive ring holding member 54 andthe first-group cylinder 25. As the rotational angle of the barrierdrive cylinder 56 is substantially small, the position of the drainholes is hardly changed, which does not influence the drainingoperation. In this example, the holes 56 h are required to be formedforward of the end of the cam cylinder 21 even if the lens barrel is inthe most retracted position so as to prevent the water drained throughthe holes 56 h from dropping into the lens barrel.

In the aforementioned example, air holes that constitute the air passageare formed in the barrier drive ring holding member 54 and thefirst-group cylinder 25. The member in which the air holes are formedmay be changed depending on the structure of the barrier block. The airpassage for communicating the barrier retraction space with the rearspace in the lens barrel may be made so long as it is located close tothe drain holes.

In the camera according to the first and the second embodiments, thelens is moved into the retracted position when it is not used, and thelens is brought into the “wide” end as the shooting position when thepower is turned on. Thereafter, the lens is set to an arbitrary positionbetween the “wide” end and the“tele” end depending on the zoomoperation. The invention, however, may be applied to the camera in whichthe lens is not driven into the retracted position when it is not used,that is, the lens is constantly positioned at the shooting position, orthe single focus camera. In this case, when the power is turned on, thebarrier drive cylinder is rotated without driving the lens so as torelease the barrier. This operation may be easily performed by providingthe barrier drive cam to, for example, the cam cylinder. If the zoomlens barrel is employed in the camera, the zoom motor can be used as thedrive source for operating the barrier.

The invention may be applied to the camera in which the lens is movedbackward and forward between the “wide” end and the “tele” end ratherthan retracting, or to the single focus camera. The embodiments of theinvention have been described with respect to the digital camera,however, it is applicable to the silver halide camera.

The invention may be formed as a camera provided with combined featuresof the first and the second embodiments.

It is to be understood that the invention is not limited to the lensbarrel or the camera that have been described in detail in theembodiments but applicable to the lens barrel and the camera in whichthe elements equivalent to those described are replaced.

1. A lens barrel comprising: a lens provided in a lens chamber withinthe lens barrel; a lens barrier that is opened and closed in front ofthe lens; a barrier drive cylinder provided on an outer peripheral sideof the lens so as to be allowed to rotate about an optical axis relativeto a member provided on an inner peripheral side of the barrier drivecylinder; a first link mechanism that rotates the barrier drivecylinder; a second link mechanism that opens and closes the lens barrierinterlocking with a rotation of the barrier drive cylinder; and anannular seal member that is provided into a space between the barrierdrive cylinder and the member provided on the inner peripheral side overan entire circumference.
 2. The lens barrel according to claim 1,wherein: the lens is allowed to move forward and backward along theoptical axis for performing an operation of zooming or focusing; and thefirst link mechanism interrupts the rotation of the barrier drivecylinder when the lens moves forward and backward for performing theoperation of zooming or focusing.
 3. The lens barrel according to claim1, wherein: the lens is allowed to move forward and backward in a rangebetween a shooting position and a non-shooting position along theoptical axis; and the first link mechanism rotates the barrier drivecylinder interlocking with the lens that moves forward and backward. 4.The lens barrel according to claim 3, wherein: the lens that has reachedthe shooting position is further allowed to move forward and backwardalong the optical axis for an operation of zooming or focusing; and thefirst link mechanism interrupts the rotation of the barrier drivecylinder when the lens moves forward and backward for performing theoperation of zooming or focusing.
 5. The lens barrel according to claim4, wherein the first link mechanism rotates the barrier drive cylinderonly when the lens moves in a part of the range between the shootingposition and the non-shooting position.
 6. The lens barrel according toclaim 3, wherein the first link mechanism comprises: a rotary cylinderthat rotates about the optical axis on the outer peripheral side of thelens so as to generate a force that moves the lens and the barrier drivecylinder along the optical axis; and a straight guide member that guidesthe lens to move straight along the optical axis, and applies a rotatingforce around the optical axis to the barrier drive cylinder that movesalong the optical axis.
 7. The lens barrel according to claim 1, whereinthe second link mechanism comprises: a drive force generation memberthat generates a drive force for opening and closing the lens barrier;and a transfer mechanism that opens the lens barrier through a transferof the drive force to the lens barrier interlocking with a rotation ofthe barrier drive cylinder in one direction, and closes the lens barrierwithout the transfer of the drive force interlocking with a rotation ofthe barrier drive cylinder in an opposite direction.
 8. The lens barrelaccording to claim 6, wherein the second link mechanism comprises: adrive force generation member that generates a drive force for openingand closing the lens barrier; and a transfer mechanism that opens thelens barrier through a transfer of the drive force to the lens barrelinterlocking with a rotation of the barrier drive cylinder in onedirection, and closes the lens barrier without the transfer of the driveforce interlocking with a rotation of the barrier drive cylinder in anopposite direction.
 9. The lens barrel according to claim 7, wherein thetransfer mechanism is provided closer to a front of the lens barrel thanthe seal member.
 10. The lens barrel according to claim 8, wherein thetransfer mechanism is provided closer to a front of the lens barrel thanthe seal member.
 11. A camera comprising the lens barrel according toclaim
 1. 12. A camera comprising the lens barrel according to claim 10.13. A lens barrel comprising: lenses provided in a lens chamber withinthe lens barrel; a lens barrier that is opened and closed in front ofthe lenses; and a barrier block that is provided near an inlet of thelens chamber so as to be movable along an optical axis, is capable ofholding the lens barrier in an open state and a closed state, comprisesa barrier retraction space where the lens barrier in the opened state isreceived, and changes a volume of a rear portion of the lens chamberaccording to a movement of the barrier block along the optical axis,wherein: the barrier block has a drain hole which communicates thebarrier retraction space with an outside of the lens barrel, and an airpassage formed near the drain hole which communicates the barrierretraction space with the rear portion of the lens chamber, such that anair flow directed from the rear portion of the lens chamber toward thebarrier retraction space is generated in the air passage when thebarrier block moves backward.
 14. The lens barrel according to claim 13,wherein: the barrier unit includes at least a part of the lenses and aholding member thereof; and apart of the air passage is an air holeformed in the holding member.
 15. The lens barrel according to claim 13,wherein a metal function member within the lens barrel is disposed inthe air passage.
 16. The lens barrel according to claim 13, wherein theair passage is sealed with a gas permeable water-repellent sheet. 17.The lens barrel according to claim 13, wherein a plurality of the airpassages are formed in the barrier block.
 18. The lens barrel accordingto claim 13, wherein: a metal function member within the lens barrel isdisposed in the air passage; the air passage is sealed with a gaspermeable water-repellent sheet and a plurality of the air passages areformed in the barrier block.
 19. A camera comprising the lens barrelaccording to claim
 13. 20. A lens barrel comprising: a lens provided ina lens chamber within the lens barrel; a lens barrier that is opened andclosed in front of the lens; a barrier drive cylinder provided on anouter peripheral side of the lens so as to be allowed to rotate about anoptical axis relative to a member provided on an inner peripheral sideof the barrier drive cylinder; a first link mechanism that rotates thebarrier drive cylinder; a second link mechanism that opens and closesthe lens barrier interlocking with a rotation of the barrier drivecylinder; an annular seal member that is provided into a space betweenthe barrier drive cylinder and the member provided on the innerperipheral side over an entire circumference; and a barrier block thatis provided near an inlet of the lens chamber so as to be movable alongan optical axis, is capable of holding the lens barrier in an open stateand a closed state, comprises a barrier retraction space where the lensbarrier in the opened state is received, and changes a volume of a rearportion of the lens chamber according to a movement of the barrier blockalong the optical axis, wherein: the barrier block has a drain holewhich communicates the barrier retraction space with an outside of thelens barrel, and an air passage formed near the drain hole whichcommunicates the barrier retraction space with the rear portion of thelens chamber, such that an air flow directed from the rear portion ofthe lens chamber toward the barrier retraction space is generated in theair passage upon when the barrier block moves backward.
 21. A cameracomprising the lens barrel according to claim 20.